Metal-filament incandescent lamp.



M. D. GRBBNGARD.

METAL FILAMBNT INGANDESGENT LAMP.

APPLIOATION FILED JAN. 30, 1913.

Patented Dec. 30, 1913.

WITNESSES ATTORNEY MORRIS D. GREENGARD, OF NEW YORK, N. Y.

METAL-FILAMENT INCANDESCENT LAMP.

Specification of Letters Patent.

Application filed January 30, 1913.

Patented Dec. 30,1913. Serial No. 745,068.

To all whom it may concern:

Be it known that I, Monnis D. GREEN- GARD, citizen of the United States, residing in the borough of Manhattan, in the county of New York and State of New York, have invented certain new and useful Improvements in Metal Filament Incandescent Lamps, of which the following is a specification, reference being had therein to the accompanying drawings, forming part thereof.

My invention relates to incandescent electric lamps, and particularly to such lamps in which metal filaments are employed.

As is well known, metal filaments are fragile and require careful supporting to prevent their becoming broken in use. Especially when the filaments are incandescent, under which condition their strength is minimized, the filament Strands will bend under their own weight, and either break or contact with the adjacent strands unless the supports are properly arranged. For this reason the lamp is usually disposed with its axis substantially vertical, and the filament is commonly wound in. substantially vertical planes between upper and lower carrying arms, thereby obviating the tendency of the filament strands to gravitate or bend. This arrangement of the filament, however, has the well known disadvantage that it causes an uneven and disadvantageous distribution of light, the greatest diffusion being in a horizontal direction, while the light from the tip end of the lamp is weakest; and inasmuch as these lamps are usually arranged overhead the downward illumination is of the greatest utility.

An object of my invention is to obviate this disadvantage and to so arrange the filament as to provide for increased downward radiation of the light, without impairing the effectiveness of the supports.

Another object of my invention is to provide improved and inexpensive means of attaching the filament to the current leads.

Still other objects and advantages of my invention will appear from the following description.

The length of filament is substantially uniform in all lamps of the same voltage, and being commonly wound to and fro between the upper and lower series of carrying arms, its length is composed entirely of a number of substantially vertical strands.

Inaccordance with my invention, I reduce either the number or length of the vertical strands for a given length of filament and utilize a portion thereof in segments disposed in a transverse plane at an abrupt angle to the vertical segments, thereby pro viding incandescent filament across the tip end of the lamp and increasing the axial illumination. These transverse segments are of such length that they have anegligible tendency to sag, and specifically they extend between and are supported by two carrying arms of the lower series, although it will be readily understood that this method of supporting the transverse segments could be variously modified.

My invention also includes various other features, and details of construction, as will hereinafter more fully appear.

I shall now describe the specific embodiment of my invention illustrated in the accompanying drawings and shall thereafter point out my invention in claims.

Figure l is a perspective view of a lamp embodying my invention. Fig. 2 is an elevation of the same as viewed fro-m the left of Fig. 1. Figs. 3 and 4: are enlarged details of the adjoining ends of a section of one of the current leads and the filament end secured thereto, Fig. 3 showing the connection before it is secured and Fig. 4 showing the connection after it is secured.

Extending axially within the usual exhausted bulb A is a glass stem or rod B, through the upper enlarged end of which enters the current leads O and C as is usual. Upon the stem B near its upper end, in proximity to the end of the leads C and G a cross rod D is secured, and at the lower end of the stem another cross-rod D is secured substantially parallel to the upper cross-rod D. These cross-rods are shown as also of glass and fused or welded to the stem.

Extending horizontally in parallel directions from one side of the upper cross-rod D are three usual filament carrying arms, E, E and E of usual or suitable material, and extending from the other side of the cross rod D oppositely and parallel to the cross arms E, E and E are two filament carrying arms and E Each of these carrying arms is provided with a hook on its outer end in which the filament engages, and these five carrying arms constitute the upper series of carrying arms for the filament. Similarly a lower series of twelve transversely extending carrying arms F, F F F F F, F F F F, F and F are carried by the lower crossarm D six on each side thereof, the first six on the side of the cross-rod underneath the upper carrying arms E, E and E and the last six on the opposite side of the cross-rod extending oppositely to the first six. These lower carrying arms are also provided on their outer ends with filament engaging hooks, and the upper and lower carrying arms are substantially of the same length, so that the filament engaging hooks of the two series on the same side of the stem are substantially in the same horizontal plane.

The metal filament G, which is of one continuous length, is secured at its ends to the current leads C and C respectively. The method of fastening the leads is illustrated in Figs. 3 and 4, in which the lead G and the corresponding end of the filament is shown, and as both ends are fastened in the same way, a description of one will sutfice for both. The end of the lead is'fiattened and the flattened end is coiled up to form a filament receiving eyelet, as shown in Fig. 3, the end of the lead being bent at an angle to bring the eyelet in line with the filament, thereby enabling the fragile filament to enter the eyelet without any turn or bend. The flattened end of the lead is coiled so that it completely encircles the filament, and after the end of the filament is entered into the eyelet as shown in Fig. 3, the eyelet is closed with a suitable tool, thereby compressing and tightly gripping the filament, as shown in Fig. 4:. Thus the connection is easily, quickly and cheaply made, and the skill which is required in the usual soldering or welding operation is dispensed with. The filament is continuously wound to and fro spirally between the upper and lower supports, each strand passing underneath and across between two opposite lower carrying arms. As shown, it extends from the lead C down to the lower carrying arm F thence underneath and across to the opposite lower carrying arm F, thence up to the upper carrying arm E, down to the lower carrying arm F underneath and across to the opposite lower carrying arm F thence up to the upper carrying arm E and down to the lower carrying arm F underneath and across to the opposite lower carrying arm F thence up to the upper carrying arm E and down to the lower carrying arm F underneath and across to the opposite lower carrying arm F thence up to the upper carrying arm E and down to the lower carrying arm F underneath and across to the opposite lower carrying arm F thence up to the upper carrying arm E and down to the lower carrying arm F and finally underneath and across to the carrying arm F and up to the current lead C Each strand, therefore, comprises two segments extending longitudinally of the lamp and one segment extending transversely of the lamp and, the filament being of one length and continuously wound over the supports, two adjacent strands have a common supporting point. The supporting points of the trans verse segments are sufliciently close together to render the segments of practicable length, while any slight stretching and sagging of these segments can do no harm. In this way a very considerable axial illumination is provided without materially diminishing the lateral illumination.

I claim:

1. A filament support for incandescent lamps comprising a stem, two cross-rods can ried at an interval thereby, and carrying arms extending from opposite sides of each cross-rod, each carrying arm being provided with a filament-engaging hook on its outer end.

2. A filament support for incandescent lamps comprising a stem, two parallel crossrods carried at an interval thereby, and carrying arms extending from opposite sides of each cross-rod at substantially right angles thereto, each cross-arm being provided with a filament-engaging hook on its outer end.

3. In a metal filament incandescent lamp, in combination with an axial supporting stem and two current leads, two cross-rods disposed at. an interval along the length of the stem, two series of carrying arms, one series supported on each cross-rod and each series comprising carrying arms extending from opposite sides of the respective crossrod, and a metal filament wound upon the carrying arms and including a strand extending from one upper carrying arm to a lower carrying arm on the same side of the stem and thence to a lower carrying arm on the opposite side of the stem and thence to an upper carrying arm on the last mentioned side of the stem.

1-. In a metal filament incandescent lamp, in combination with an axial supporting Stem and two current leads, two cross-rods disposed at an interval along the length of the stem, two series of carrying arms, one series supported on each cross-rod, and each series comprising carrying arms extending from opposite sides of the respective crossrod, and a metal filament secured at its ends to the respective leads and wound continuously between the successive carrying arms of the two series to form a plurality of strands, two of the filament strands extending respectively from a lead to a lower carrying arm and thence transversely to another lower carrying arm and thence to an In testimony whereof I have afiixed my upper carrying arm, and the other strands slgnature 1n presence of two witnesses.

extending, respectively, from an upper car- MORRIS D GREENGARD rying arm to a lower carrying arm, and thence transversely to another lower carry- Witnesses:

ing arm and thence to another upper carry- WM. A. KELLY,

ing arm. VICTOR D. BORST.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. C. 

